Quine’s criterion of ontological commitment

problems of ontology

...of existence is connected with the question of what entities a theory commits its holder to or what its “ontology” is. The “predicate of existence” just mentioned recalls Quine’s criterion of ontological commitment: “To be is to be a value of a bound variable”—i.e., of the x in ($x) or in ("x). According to Quine, a theory...